The present invention relates to rotary valve and, refers more particularly, to a rotary valve for vacuum service use.
Prior rotary valves of which we are aware, are in the main used for pressure service. These valves of which U.S. Pat. Nos. 3,297,052; 3,796,232 and 3,851,669, inter alia, are representative, generally are constructed of many parts arranged in somewhat complex construction including tight mechanical sealing connections being made between the several parts in effort to insure non-leakage character in the valve during use. Also, these prior pressure service rotary valves are almost always made of machined parts which fact increases valve costs substantially, the constructions of these valves not readily being adapted for, e.g., manufacture by plastics molding techniques. Further, pressure line connection to the valve is usually made with threaded connections and these connections sometimes represent a problem initially of poor manufacture with attendant leakage or in time with use can become a leakage source. Further such constructions do not provide simplified, inexpensive valves for vacuum use service, particularly in the respect that the service use itself be employed as an adjunct in effecting sealing of the valve. Glass valves have been used for vacuum service, particularly in laboratory situations, but these types are somewhat costly and in time with continued use, present system leakage problems.